Flow reservoirs are known from the prior art, e.g., U.S. Pat. No. 6,536,687 B1 and FR 2 774 928-A. These include a container made from plastic and a cover that can be placed on the container for closing the container. There are attachment means on the top side of the cover for setting and fastening the flow reservoir on a paint spray gun. Here, the flow reservoir is set on the paint spray gun “upside-down,” thus with the cover side pointing downwards. The paint in the flow reservoir then flows downwards, due to gravity, into the paint inlet channel of the paint spray gun. To enable the gravity fed flow of the paint, the pressure within the paint reservoir must be equalized. Here, as described in the mentioned publications, a ventilation opening is punctured in the container floor or in the side wall of the container near the container floor by means of a needle after the paint container has been set on the paint spray gun “upside-down,” thus with the container floor pointing upwards.
To form the ventilation opening in the container wall, a separate pointed tool, e.g., a needle or a spike, is required. Such a tool is often not available. Furthermore, puncturing the container wall, which is generally made from hard plastic, with a suitable pointed tool has also proven to be difficult. In addition, there is the risk that plastic chips or parts will fall into the paint in the paint reservoir due to pressing an opening in the container wall.